Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the most extensively used method employed to color hair is to color hair by an oxidative dyeing process employing hair coloring systems utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, and 5-amino-2-methylphenol. A majority of the shades have been produced with dyes based on p-phenylenediamine.
It is desirable that compositions used for the dyeing or coloration of hair be such as to provide overall color fastness of the dyed hair. Accordingly, the hair dyes with the compositions of the present invention should resist loss of color occasioned by washing, by acid perspiration, and by abrasion. Another desirable feature is that such compositions evidence color fastness evidence with minimal change of color in the blue direction due to the effect of acid perspiration. It is especially desirable that such compositions with such improved color fastness characteristics be available for dyeing or coloring hair purple, or to contribute chromophores in the purple spectrum to hair dye product compositions.